The invention relates generally to an electrochemical cell, and in some specific embodiments, to a high-temperature, rechargeable electrochemical cell, and related devices.
A battery is an essential component used to store a portion of the energy in mobile systems such as electric vehicles, hybrid electric vehicles and other types of vehicles and non-vehicles (for example, locomotives, off-highway mining vehicles, marine applications, buses and automobiles), and for stationary applications such as uninterruptible power supply (UPS) systems and “Telecom” (telecommunication systems). The high-temperature sodium-metal halide electrochemical cells are generally targeted for use in locomotives; telecommunication, and uninterruptible power supply (UPS) batteries. These cells could potentially offer high energy density, high power density, longer cell life, and lower cost-requirements for many of these applications.
Normally, a battery is made up of many cells. Current development of these batteries is focused on performance and cell life. A number of factors can affect performance, and limit the cell life. The primary factor may be unreliability of a separator. The most common separator used in these cells is beta″-alumina solid electrolyte (BASE), which is a sodium conducting ceramic.
It should be noted that thermal cycling, pressure differential, sodium-wicking, and vibrations in the cell, during use, may damage the separator in some circumstances. The damaged separator may lead to electrochemical corrosion of the casing (e.g. a steel casing), and a large thermal excursion in the cell. Usually, when the separator breaks, a metallic short is formed, allowing the battery to operate with the failed cell. However, in some cases, high temperature conditions, combined with the corroded cell casing, may allow the cell's chemical components to breach the casing, which can short-out the entire battery.
Development work has been undertaken on different battery designs to avoid and/or solve the corrosion problem. One way to avoid the corrosion of the cell is by providing effective thermal and electrical conductance between the core of the cell and the casing. However, there may be significant limitations in current designs to perform these functions effectively. Also, the currently available designs are not suitable to reduce or prevent the corrosion of the housing significantly.
It would therefore be desirable to develop a new cell design, with improved thermal management and improved reliability, for various battery applications.